ggml-cuda: fallback to F32 on device without BF16 hardware acceleration (#28846)
* ggml-cuda: fallback to F32 on device without BF16 hardware acceleration: (Nvidia >= AMPERE, AMD >= RDNA3 or = CDNA)
* apply logic to NVIDIA as well
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Co-authored-by: Johannes Gäßler <johannesg@5d6.de>